Circular stapling instruments are well known in the surgical art for bowel surgery. An example of such a device is the Endopath ILS ECS 25 Endoscopic Curved Intraluminal Stapler made by Ethicon Endo Surgery Inc. Many circular stapler patents exist, for example U.S. Pat. No. 4,207,898 to Becht, U.S. Pat. No. 4,351,466 to Noiles, U.S. Pat. No. 5,292,053 to Bilotti et al., and U.S. Pat. No. 5,344,059 to Green et. al.
Currently, many circular stapling instruments employ designs in which the user has to manually lock a firing trigger to lock a corresponding staple driver when an anvil assembly is in an open position out of firing range, or unlock a firing trigger to unlock the corresponding staple driver when the anvil assembly is in a closed position within firing range. This requires user activation and may lead to misfiring of the instrument. Some designs have automatic locking mechanisms, but after the firing trigger and corresponding staple driver are fired, the automatically locking mechanism no longer automatically locks the firing trigger and corresponding staple driver in place thereby allowing the circular stapling instrument to be inadvertently fired again.
An automatic locking mechanism for a circular stapling instrument is needed to address these issues.